1994 g20 thump thump thump
 

When the van first starts 2 of 3 times it will make a series of thumps then smooth out. Runs smooth. 77000 miles.

Thumping is coming from under dog house, or rear? Moving yet, or still sitting at idle? Try taking the house off when cold and start. Listen for origin and look for worn/loose mounts around motor and exhaust.

Thump thump thump
 

Thanks! The noise seems to be from the dog house. Only upon starting and stops after a few thumps. I'll check under doghouse